Cog Neuro Lec 7 - Motor Coordination

what is electromyography? (EMG)

like EEG but for the muscle

what happens to your triceps when your bicep is flexed? and visa versa

triceps relaxed when bicep is flexed

bicep is relaxes when triceps is flexed

what causes muscle contractions?

Ach releasing

what does botox do to Ach?

suppresses release to cause muscles to relax (ironic)

what does black widow venom do to Ach

stimulates release causing muscle spasm, potential impact to respiration (can’t breath)

what is Myasthenia Gravis

grave muscle weakness

• fewer receptors and more that don’t operate optimally

• caused by membrane damage and causes difficulty moving

what is an efferent signal?

motor output (ventral)

what is an afferent signal

somatosensory input (dorsal)

what is the corticospinal tract and explain its path

cerebral cortex → spinal

originates in the primary motor cortex _. midbrain → medulla (cross at meduall pyramids) → spinal cord

contralateral 

dermatome

zones of the body

plegia (plegic)

paralysis of a body region

paresis (paretic)

weakness/partial paralysis

quadriplegia

inability to move all four limbs

may be caused by damage above T1 (eg. C5) 

• carrying somatosensory and motor pathways for the entire body high up

paraplegia

inability to move the trunk or lower two limbs

caused by damage below T1 (eg. T4)

is spinal injury more commonly bilateral or ipsilateral?

mostly bi because the areas that control either side are basically on the same disk/close to each other

is brain injury more commonly bilateral or contralateral?

usually contralateral because of the tracts

hemiplegia

paralysis of half of the body

hemiparesis

weakness/partial paralysis of the body

what is the bundle of motor fibers that dive down to the brain stem

internal capsule 

from the internal capsule go

medullary pyramids where it crosses and goes to the spine accordingly

what happens if your internal capsule is damaged during a stroke

you loose all motor control contralateral to where the stroke was

central pattern generator

code complex movement that is highly learned and over-practiced

motor circuits in the spine can control walking without the brain

hierarchical control of movement

activating a central pattern generator that simulates combination of movements necessary to do an over-practiced test 

why do cnetral pattern generators only exist in animals

because they have 4 legs and can be supported by the other two legs when the bottom ones are cut

can an animal regain ability to move their legs if the spinal cord is damaged?

yes, if Schwann cells are introduced

primary cortex role (M1)

codes for the direction of movement

what is a tuning curve and how does the M1 use it

it is like a normal distribution where the brain more favourably moves in a certain direction and then not so much in the others the more it deviates. 

if your moving left 180 degrees, how would your neurons react?

neurons responsible for moving to the left and neurons that are responsible for moving up would work together (in vectors) to make an angle.

how can population vectors predict the direction of forthcoming movement?

depending on the vector of neurons active, we can track which neurons have a favourable reaction to a certain direction

intraparietal sulcus: parietal reach region (PRP)

reaching

lateral intraparietal area (area LIP)

eye movements

anterior intraparietal area (AIP)

grasping

what is the “where” pathway?

dorsal stream

what is the “what” steam?

ventral stream

what happens to your ability to “reach” with your eyes (saccade memory-guided movement) if you damaged the parietal reach region

nothing, it works completely fine, this is called optic ataxia : cannot use vision to guide action

what happens if you TMS to aIPS (anterior intraparietal area)

disrupts online correction of movement as your making this movement

damaged in optic ataxia as well

PMC (premotor cortex)

observational learning and understanding the actions of others

mirror neurons

in the PMC where neurons are active if your watching someone do something or doing it yourself or hearing action sounds

what kinds of sounds does the PMC care about?

action sounds, if its white noise or anything else, it does not care because it doesn’t reflect something YOU can do

peripersonal and extrapersonal mirror neuron

extrapersonal mirror neurons only activates if its far from you

peripersonal mirror neurons only activates if its in your personal space because you can work on them immediately

what is the most prominant mirror neuron

neurons that care about peripersonal and extrapersonal spaces

after how many cm does something have to move to you for your peripersonal mirror neurons to have peak activation?

about 28cm

is your peripersonal space a fixed space?

no, if you have something blocking you from reaching to something in your peripersonal space, it activates extrapersonal neuron

it also expands when we have some time of tool or arm extended that increases our reach limits

supplementary motor area (SMA)

holds information about sequence involved in remembering a detailed motor sequence like sports or a dance routine 

role of the cerebellum

smooth, efficient, coordinated motor movement

cerebellar ataxia

difficulty with coordinated movement

• impaired voluntary coordination of movements due to cerebellar lesion

dysmetria

dys: dysfunction

metria: reach

cannot reach for things smoothly because of cerebellar ataxia

dysarthria

severe slurring of speech because they lost fine motor control of larynx 

cerebellar posture, gait

cannot walk properly, very discoordinated 

what happens if your born without a cerebellum?

can function quite well because of neuro plasticity, but very bad if you lose it later in life

progression of the methods section of an article

participants → task #1 (key IV and DV’s) → task #2 (key IV and DV’s)